1. Field of the Invention
The present invention relates to an electronic device, and more particularly, to an electronic device with an automatic backup or an overwrite file function.
2. Description of the Related Art
The applied techniques to the computer and data processing are continuously changed. In addition to use the internal hard drive to store a great amount of data, more data storage devices connected to the computer or server by means of external transmission are used for data back-up and storage now. The common data storage devices, for example, include the memory card, the flash portable disk, the recordable/rewritable optical disc, the large capacity micro drive, or the disk array system.
Using the external hard drive as an example, a user stores a data file in an external hard drive for the convenience of carrying, and the external hard drive can be used as a data transmission facility between two computers. For instance, the incomplete work can be saved as a file into the external hard drive in the office, and the external hard drive can be plugged into the home computer to continue the office work at home. Meanwhile, the system regards the external hard drive as a data storage unit and read the data file from the external hard drive in order to revise the data. In order to avoid the loss and damage of important data, the user usually backs up more than one copy of the file with important data into the internal hard drive of the computer, and the data file will be named the same for easy recognition. However, the above-mentioned backup operation is manually operated, which is inconvenient to the user and error prone. Consequently, the files cannot be easily shared.
FIG. 1 schematically shows a flow diagram illustrating the operating principle of a conventional disk array system. The main board 1 is exemplified herein. When a first data stream is provided to a disk array controller 20 by a CPU (Central Processing Unit) 10, the first data stream is disassembled into a plurality of data blocks 1˜2N and stored into the hard disks of two disk drives 30 and 40. When the disk array controller 20 is configured to operate in the RAID 0 mode, the data blocks 1˜2N will be equally disassembled into two portions and then respectively written into the hard disks of the two disk drives 30 and 40. Since these two disk drives 30 and 40 synchronously perform the read or write operation on the data blocks 1˜2N, the speed of data backup can be doubled.
FIG. 2 schematically shows a flow diagram illustrating the operating principle of another conventional disk array system. When the disk array controller 1 is configured to operate in the RAID 1 mode, two copies of the data blocks 1˜N are automatically made and simultaneously written into the hard disks of the two hard drives 30 and 40. Since both disk drives 30 and 40 store the same data blocks 1˜N, once one of the disk drive units is malfunctioned, the same data blocks can be read from the other disk drive, such that the data loss is avoided. Accordingly, the RAID 1 mode is also known as the disk mirroring mode.